Technical Field
The present invention relates to an additive composition for polymer-modified asphalt, a polymer-modified asphalt composition including the same, and a method of preparing the same, and more specifically to an additive composition for an asphalt which may maintain physical properties of polymer-modified asphalt, reduce viscosity, and improve processability and pavement performance, a polymer-modified asphalt composition including the same, and a method of preparing the same.
Related Arts
Examples of asphalt modifiers include rubber-based modifiers, thermoplastic resin-based modifiers, thermosetting resin-based modifiers, hydrocarbon-based modifiers, fillers, fibers, antioxidants, reducing agents, etc. Examples of the rubber-based modifiers include a natural rubber, a styrene butadiene rubber (SBR), a crumb rubber, or the like, and examples of the thermoplastic resin-based modifiers include styrene butadiene styrene (SBS), ethylene vinyl acetate (EVA), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyethylene terephthalate (PET), etc. Examples of the thermosetting resin-based modifiers include epoxy resins, urethane resins, acrylic resins, phenol resins, petroleum resins, or the like, and examples of the hydrocarbon-based modifiers include natural asphalt, etc.
Among them, a polymer compound, especially, an aromatic vinyl hydrocarbon-conjugated diene block copolymer such as a styrene butadiene styrene (SBS) block copolymer is known to be effective for improving properties at high and low temperature. SBS is a copolymer in which a soft butadiene block and a hard styrene block are bonded. When SBS is dissolved in asphalt at a high temperature, the viscosity and elasticity of asphalt increase, and thus resistance to plastic deformation at a high temperature increases, and the flexibility of asphalt at a low temperature increases, resulting in an increased resistance to cracks at low temperature.
However, when SBS is used as an additive, the viscosity of an asphalt composition increases, a large amount of energy may be consumed for the manufacture and pavement of asphalt. Further, since SBS has low affinity for asphalt, polymer-modified asphalt may be separated into a non-uniform phase.
In order to solve such a problem, a small amount (less than 5 wt %) of sulfur is added to polymer-modified asphalt as a phase separation stabilizer. However, when sulfur is added, the viscosity of the asphalt composition may increase, and hazardous substances such as sulfur oxides may be discharged.
Accordingly, there is a need for the development of an additive composition for polymer-modified asphalt to which less sulfur is added during manufacturing the polymer-modified asphalt, and which has low viscosity and may maintain properties of existing polymer-modified asphalt.